Cannot fulfill order items through rest api

[hoannguyen02]

Hi everyone,

We are trying to fulfill order items by using fulfillment api with custom app credentials but the response is html, not json. May I ask how we can return as json like documentation. Thank you very much

Here is request payload

{
    "fulfillment": {
        "line_items_by_fulfillment_order": [
            {
                "fulfillment_order_id": 6757436850239
            }
        ],
        "location_id": "36162764863"
    }
}

The result is in screenshot below